Shipping case



April 27, 1954 w. GEISLER 2,676,745

SHIPPING CASE Filed Sept. 12, 1949 SOLUTION OF LATEX AND SODIUM SILICATEINVENTOR WILLIAM GEISLER ATTORNEYS Patented Apr. 27, 1954 WilliamGeisler, Tenafly, N. J assignor to Wilbro Corporation, New York, N. Y.,a corporation of New York Application September 12, 1949, Serial No.115,310

This invention relates to shipping cases or cartons such as now almostuniversally employed for the Shipping of cans, bottles, packaged goods"Such cases or cartons and other commodities. are usually formed from aSingle blank of double-faced corrugated paper which is cut and scored toprovide four connected side walls with integral flaps to be folded overto form the ends of the carton when erected and packed. Such cartons,when kept dry and properly handled, are quite satisfactory even forheavy loads such as cans of paint and the like, but when the paperabsorbs moisture, either from getting wet or in storage in a humidatmosphere, the paper is considerably weakened and is apt to give way,particularly at the score lines where the edges of the can tend to cutthrough the softened paper.

The object of the invention is to provide a a carton of this standardtype wherein the carton is strengthened at the fold lines and is also atthe same time rendered resistant to the absorption of water, so that thecarton maintains its normal strength under conditions which heretoforehave caused the carton to weaken in the manner I have described.

The carton may be strengthened by the method herein described at thefold lines only or throughout the entire surface of one or both faces ofthe blank. In protecting the score lines only of the carton a solutionwhich serves to toughen the paper is applied to the inner surface of thecorrugated board at the score lines.

In the accompanying drawing I have illustrated a carton blank ofconventional configuration with its score lines treated in accordancewith my invention, and in the legend on the drawing I have recited theingredients of the applied solution.

The principal ingredient of the preferred toughening solution is latexin the form ofa water emulsion having the proportions of approximately6()% latex and 40% water. To this is added a water dispersion of claysuch as commonly used as a filler in the manufacture of molded rubberarticles, the solid content of the dispersion being about 60%. To themixture of latex and clay there is added a sodium silicate solutionwhich may also have a solid content of approximately 60%. The latexemulsion constitutes about 60% of the toughening solution with the claydispersion constituting 20% and the sodium silicate solution 15%. Theremaining is made up of sulfur about 3%, a, suitable wetting agent, forexample, sodium polyacrylic acid, about 1% and a suitable accelera- 2Claims. (Cl. 22916) tor, for example, a mixture of tetramethyl thiuriumdisulfide and benzothiosol disulfide. The ingredients are mixed togetherat room temperature and with the water content above stated, havesufficient fluidity to be applied to the surface of the carton blank bya roll coater of ordinary construction having an applying roller of thedesired pattern. The solution may be made thinner for spraying or moreconcentrated, if desired.

The proportions of the ingredients above speci fied are not critical.Generally speaking, the toughness of the coating, that is, itsresistance to puncture and abrasion, is increased by adding to thepercentage of latex. The chief function of the sodium silicate is toincrease the stiffness of the treated board while the clay serves togive body to the coating which remains on the surface of the carton.However, even where the board itself has ample stiffness and it isdesired merely to toughen the board against puncture and abrasion, thesodium silicate is preferably not omitted altogether, as it apparentlyhardens the coating as well as stiffens the board.-

This compound, when applied to the surface of the board along the scorelines in stripes one inch wide in an amount of, say, one pound ofsolution to square feet of surface, will, after drying, render the boardmuch less water-absorbent in the treated portions than in the otherportions, and will also toughen and stifien the board so that itsresistance to puncture is greatly increased and its capacity to supporta stacking load, particularly when the untreated portions of the boardare softened by water absorption, is also greatly increased.

The solution may be applied to the finished blank at the same time thatthe blank is cut and scored, and may be readily heated to dry and setthe solution as the cut and scored blanks are delivered to the stackingmechanism.

The solution may be applied to the entire'surface of the corrugatedboard on one or both sides after the board is finished, or the solutionmay be applied to the surface of the paper sheet from which the facingsof the corrugated board are made before the board is formed. In eithercase the board should be heated to vulcanizing temperature after thesolution is applied, which may be readily accomplished by feeding thecoated sheet, either the paper sheet or the corrugated board, as thecase may be, through a conventional heater or the kind employed forvulcanizing rubber solutions applied to textile fabrics.

3 4 Iclaim: References Cited in the file of this patent 1. As a newarticle of manufacture, a paper carton having portions of its innersurface UNITED TE PATENTS treated with a toughening solution containingNumber Name Date latex and sodlum slhcate. 393,899 Haines Dec. 4, 18882. A paper carton composed in whole or in part of a sheet of paper boardhaving fold lines f jazi Deventer formed in the board, said fold linesbeing treated 2,259,035 Gillican Oct. 14, 1941 232:? a solution contammglatex and sodium 5111- 10 2,350,161 Gloor May 30 1944

1. AS A NEW ARTICLE OF MANUFACTURE, A PAPER CARTON HAVING PORTIONS OF ITS INNER SURFACE TREATED HAVING WITH A TOUGHENING SOLUTION CONTAINING LATEX AND SODIUM SLICATE. 